1. Field of the Invention
The disclosures herein relate to a testing method for testing a semiconductor device and a testing device for testing a semiconductor device. More specifically, the disclosures herein relate to a testing method and a testing device for testing a semiconductor device including an overheat protection function that is activated when a temperature of the semiconductor device resides in an overheat protection function activating temperature range and is deactivated when the temperature of the semiconductor device resides in an overheat protection function deactivating temperature range.
2. Description of the Related Art
Semiconductor devices generally include an overheat protection circuit so as to prevent the semiconductor device from being damaged or deteriorated due to overheating caused by an increase in an ambient environment temperature or breakdown of a cooling fan. The overheat protection circuit is configured to be activated when the semiconductor device reaches a predetermined temperature or above.
In the semiconductor device including such an overheat protection circuit, whether a temperature at which the overheat protection function of the overheat protection circuit is activated falls within an allowable temperature range is tested. Examples of such a temperature range testing method may be given as follows.
One of the temperature range testing methods includes heating the semiconductor device by a handling device in which the lower threshold of the allowable temperature range is set, and ensuring that the overheat protection function is not activated in a state of being heated in the above manner. The temperature range testing method further includes subsequently heating the semiconductor device by another handling device in which the upper threshold of the allowable temperature range is set, and ensuring that the overheat protection function is activated in a state of being heated in the above manner.
Another temperature range testing method is disclosed in Japanese Patent No. 2852992 (hereinafter referred to as “Patent Document 1”). The disclosed testing method includes a first process of heating a semiconductor device by utilizing a handling device in which the lower threshold of the allowable temperature range is set and subsequently ensuring that the overheat protection function is not activated in a state of being heated at the set lower threshold of the allowable temperature range, and a second process of measuring a period from a self-heat generation initiating time at which the semiconductor device initiates self-heat generation to the overheat protection function activating time at which the overheat protection function is activated and subsequently ensuring that the measured time falls within a predetermined time.
The overheat protection function of the overheat protection circuit is generally configured to be activated when there is a possibility of damaging the semiconductor device due to overheating, and hence the overheat protection function of the overheat protection circuit is designed to be activated when the temperature of the semiconductor device reaches the absolute maximum rating temperature or above. Accordingly, the lower threshold of the allowable temperature range within which the overheat protection function of the overheat protection circuit is activated may be higher than the absolute maximum rating temperature of the semiconductor device. Further, ordinary operations of the semiconductor device may also be tested under the absolute maximum rating temperature or below.
Thus, the testing method disclosed in Patent Document 1 may require carrying out two tests utilizing two handling devices, one for testing the overheat protection circuit and the other one for testing the operations of the semiconductor device under the absolute maximum rating temperature or below, or utilizing one handling device by altering the settings of the handling device appropriately for each test. Further, in a case where the semiconductor device is allowed to generate heat by itself (self-heating), the semiconductor device transfers heat from its package surface and measuring terminal. Accordingly, a subtle difference of a contact condition in the measuring terminal or a subtle difference in the testing environment temperature may vary the time required for initiating the activation of the overheat protection function, which may result in poor reproducibility.